Temperature control for heat exchange unites



Jan. 29, 1946.

TEMPERATURE R. J. 4STEWART CONTRL FOR HEAT EXCHANGE UNITS Filed Mau-.m- 2, 1942 LBBW-ER.

`bonator or saturator.

Patented Jan. 29, 1946 TEMPERATURE CONTROL FOR HEAT EXCHANGE UNITS j Robert J. Stewart, Baltimore, Md., assgnor to Crown Cork & Seal Company, Inc., Baltimore. Md., a corporation of New York 'Application March 2, 1942, Serial No. 433,069

16 Claims.

The present invention relates to temperature controls for heat exchange units and, more Iparticularly, to such a control for a refrigeration unit used in cooling an intermittently flowing stream of water.

In soft-drink bottling plants, it is necessary to cool Water before it "is carbonated, since carbon vdioxide gas will more readily go into solution when the water is at a low temperature. For this reason, it is usual to run the water through a control for'heat exchange units whereby a liquid or other substance-can be cooled to an optimum extent while flowing and without danger of freezing occurring when flow stops.

a cooling; unit before it is flowed to the carwater flows to a lling machine which places the carbonated water and syrup in bottles.

' The practice in bottling plants is to providefor a minimum level of carbonated water` in the carbonator. When the water drops to this level, a water pump is placed in operation to force water through a cooler and into the carbonator until a maximum level is reached, when the sup- After carbonation, the

ply of water is discontinued and ilow through the cooler therefore, stops, leaves water stand- .ing in the cooler. During yall this operation, the filling machine is constantly draining water from the carbonator. In an average plant, the water `punriip will be in operation about ten minutes l-out 'of each twelve minutes,'with the filler in The invention may be generally described as comprising a control whereby the eifective temperature of the heat exchange unit will be at lleast partially controlled by the actuation of the water supply means or pump.

be obtained from a cooling unit if a marked temperature differential can be safely maintained while the water is'running. For example, if a refrigerating unit of the ooded type is so controlled that the vpoint at which evaporation occurs is raised nwhen water flow stops and it, therefore, cannot freeze standing water, such a unit can normally/be maintained under extremely low pres/sure and thereby cool a great volume of ,wateryy to a temperature just above freezing. In addition, a refrigerating unit which includes a control to' prevent it from freezing standing water can be operated to cool a moving body of water to a temperature veryclose lto freezing.

Another objectof the invention is to provide a control of the type described in the preceding objects, and which control is of optimum simplicity.

That is, since'fthe unit must be set to insure lthat tween the water and the refrigerating agent be- It has heretofore been proposed to control heat exchange units according to whether flow of the liquid to be cooled is occurring. However, such arrangements have been responsive to the phy- It will be understood, that the description of the application of the invention to a cooling unit for water is merely for purposes of illustration 4t since the application of the invention to any heat cause the eiective temperature of the latter must always be substantially above freezing.

An important object of the present invention is to provide a control for heat exchangeunits y exchange device and its control within critical limits will be quite apparent.

` Other objects and advantages of the invention will be apparent from the following specification and accompanying drawing wherein:

Figure 1 isa diagrammatic showing of a control arrangement and circuit included in the invention; l

Figure 2 is a diagrammatic showing of a modified control; and f It will bev apparent that greater elciency canv sical presence of liquid, rather than to operation 'f of the liquid supply means and they, therefore,4

Figure 3 diagrammatically shows an additional modied arrangement.

Referring to Figure l, the numeral I U designates an electric motor driving a water pumpvi I. Water to becooled is delivered to the pump'from any suitable source through the pipe I2 and ows from thepumpfthrough pipe I3 to a water coil |4 positioned in a re'frigeratingA or heat exchange unit I5. Coil I4 extends to a water line I8 lead ing to a carbonator I1. When carbonated, the water settles in the lower portion of the carbonator and actuates floats I8 and |8a which, as

I hereinafter described, serve as controls upon the operation of the electric motor I0. -As is the usual practice, during the normal operation of the bottling plant, water will be continually withdrawn from the carbonator through outlet pipe I 9 to flow to the reservoir of a iilling machine. However, the water pump Il is normally only operated at intervals., For example, thewater pump oi' a carbonator may be actuated ,f or about ten minutes out' of` each twelve minutes. That is, the water level drops due to the drain upon theA carbonator by the ller and the water pump then -operates to raise the level and accumulate an excess supply. The motor then stops and the waterlevel will not drop to lower the iloat' to Ma critical position for another two minutes.

The heat exchange unit `I isof the flooded type and receives liqueiied refrigerant or other heat exchange medium readily vaporizable .at

' frigerant.

- ually operated switch diagrammatically shown by a lead 6I to the power line 46.

to be fully opened by a valve opening coil 3|,

and is urged toward a more nearly closed position with-regard to the vseat by a spring, not shown.` That is, whenvalve vopening coil 3|A is energized, the valve 29 will be raised to a more widely opened position with respect to seat 3|)4 s that lower pressure will -be maintained in theV unit" I5 and the point ofA evaporation of the refrigerant lowered so that it will have a greater cooling eil'ect. deenergized, the spring associated with valve 29 will move the latter to such position that the suction line 28.will be'more nearly closed .and a higher pressurev will be maintained in unit I5, thereby reducing the cooling effect 'of thev re- By the construction disclosed in Figure 1, when the electrical circuit hereinafter described is set to 'automatically control the valve, coil 3| will nQrmally be energized to hold valve 29 However, when the coil 3| is 'I'he Figure i circuit whereby valve opening coil 3| is controlled as stated above is as follows: The numeral 40 designates a power line adapted to be connected by a contact 4| with a lead 42 to motor I0. The numeral 43 designates a second power line adapted to be connected by a contact 44 with a motor lead 45. Numeral 46 designates a third and common return power line arranged to be connected by a contact 41 with a motor lead '48. are carried by a contact supporting element 5D actuated by a switch holding coil 5|. From power line 43 a wire 52 extends to one end of coil A leadalso extends from power line 43 to one end of valve opening coil 3|. A lead 58 is connectedlto the other end of holding coil 5I, lead 58 continuing to the contact 59 of a manat-60 and which has two closed positions. The movable contact element of switch 60 is connected A mercury type switch 62 controlled by theoat I6 of carbonator I1 is' connected'by a lead 63 to lead 58 and by a lead 64 to aline 65 which extends between the other fixed contact 66 of manual switch 60 and the thermostatically controlled switch,35. The other side of thermostatic switch 35 is joine by a lead 66 to-lead 58a. y

The second float I8a in carbonator I1 is so mounted that a second mercury type switch 62a controlled thereby will be operated simultaneously with the switch 62 of float I8. One contact of switch 62a is connected by a lead .64a with lead 64 and its other contact is connected to lead 66 by a lead 66a.

vIt will be understood from the foregoing that the floats I8 and I8a Acause their switches 62 and 62a to close when the lwater reaches a predetermined low level, the vswitches remaining closed until the water reaches a predetermined high level. f

The operation ofthe electrical circuit arrangement of Figure 1 is as follows: When-manualv switch 60 is moved to bring its diagrammatically indicated righthand contact blade-10 against y iixed contact 59, which is the manual position,

wide open so long as Amotor I0 is operating the i. e., the position used to test run /the apparatus and which can only be maintained by an operator holding the switch closed, current will flow from power line 46 through lead 6| to the .mov-

able contact 10 and thence through lead 58 to the switch holding coil 5| and then to power line 43, The lcontact supporting element 50 will there-l by be moved to cause the power lines 40, 43 and 46 to be connected to motor leads 42, 45 and 48 so that water pump motor I0 will be -operated and pump II will supply water'to unit I5 from which it will ow to the carbonator I1.

At the same time, thevalve opening coil 3| will be energizedif theoats 8y and |8a areinlowered position due to the fact that the .coll is now in parallel with the above holding coil circuit A through lead 55 andleads 58a, 66. 66a, switch 62a,

to the temperature of the water in coil I4 is opened. When switch 35 is opened, coil 3| will 'be deenergized, valve 29'will move to a more nearly closed position and a higher pressure will be 'maintained in unit I5.

lead 64a, switch 62, and lead 63. As a result, the water iiowing through unit I 5-will be cooled to 'maximum extent, bearing in mind its rate of Aand thereby. reducingv the cooling effect of unit I I6. -It will be observed that the above circuit is entirely "independent ofv any control by the ther-v mostatic switch 35. When manual'switch 94 is actuated to move its The contacts 4|, 44 and 41 l Switch 60 is of such type that contact 1I will remain engaged in closed position until it is manually released for snap movement to the off position indicated in Figure l. `When moving contact 1I engages. contact 66 current will flow through coil 5| by the following holding coil actuating circuit: from power line 46 through lead 6|, movable contact 1I lead 65, float controlled switch 62, and

leads 63 and 58 to coil 5I to energize the latter and move the contact supporting element 50 to cause current to be supplied motor II). However,

it will be obvious that coil 5| cai-mot be energizedv unless the water level is low in carbonator I1 and,

for that reason, motor I will not be operated except under such condition.

Assuming that the water supply is low the mercury switch 62 to close and thereby energize holding coil to operate motor I0, the 'coil 3| which controls lrefrigerant suction valve 29 will alsobe energized because it is in parallel'with holding coil 5|, through switch 62a. Valve 29 will thereby be moved to its fully opened position to enable the refrigerant in unit I5 to evaporate 4at lower pressure and thereby cool the water supplied by pump to the lowest desired temperature.

The above opening of valve 29 will occur regardless of whether thermostatic switch 35 is open to causel or closed because the latter is simply in parallel with the holding coil actuating circuit described above as well as in parallel with the circuit described above for energizing the coil 3|. However, if thermostatio. switch is open because the temperature of the water standing in ,coil I4 is low, it will close immediately water moves into the coil from pump I I.

Motor I0 will operate until the water level in carbonator ,I1y rises to a predetermined point, when mercury switch 62 will be opened to cause holding coil 5| to be deenergized and thereby stop motor I0. but since switch 60 is still closed through contact 1|, current will flow to the suction valve opening coil 3| through the parallel and alternatively effective circuit including lead '65, thermostatically operated switch 35, lead66, lead 58a, and, on the opposite side of the coil, through lead 55 to power line 43. As a result, valve 29 will be heldv in its fully opened position until the water temperature drops suciently to cause thermostatically operated switch 35 to be opened. When this occurs, coil 3| vwill be deenergized so that suction valve 29 may move to a more nearly closed position, thereby maintaining a higher pressure in the unit I5 and preventing the non-flowing water Vfrom being cooled to the same extent as when valve 29 is wide open. v

When the water level of the carbonator I1 `again drops, holding coil 5| will be again energized to start the motor I0 and suction valve coil 3| will also be immediately energized to fully open valve 29 so that the incoming water 'will be promptly cooled. rI he thermostaticswitch- 35 will then be closed for a new cycle of its operation because the incoming water will suiciently raise the temperature of the heretofore standing 'water in coil I4 to cause such closing.

It will be noted that by the Figure 1 circuit, there is no lag in placing the unit I5 under the desired low pressure when the flow of water starts. There is a lag in increasing the pressure in the unit I5 when the owofwater stops but this is of no consequence in operation with a carbonator because the lag only results in the water becoming somewhat cooler and thereby balances the slight lag in .cooling which might be encountered in some installations because of the initial `entry of Warmer water when the motor starts. In addition, in carbnating water, there isno objection tohaving the water slightly cooler than the desired setting, though there is a substantial objection to having the Water somewhat warmer than desired. Y,

Referring to Figure 2, the structure disclosed therein is identical with that disclosed in Figure 1 except that only one float I8 land a float operated switch 62 are used. The circuit is also identical with that'of Figure 1, except that by the Figure 2 arrangement, the leads 64a and 66a and switch 62a are omitted so that the holding coil 3| and a float operated switch (such as 62a of Figure l1) are not in parallel with switch holding coil 5I. The Figure 2 arrangement causes holding coil 3| of valve 29 to be controlled to some extent by the temperature of the water. However, as hereinafter explained, the water temperature depends to a large extent upon whether pump I I is supplying water to coil I4.

Ihe operation of the Figure 2 circuit is as follows: When the movable contact 10 of switch 60 is moved to closed position by an operator, as would be the case for testingjthe circuit would be from common return line 46 through lead 6|, moving contact'10, contact 59, leads 58, switch holding coil 5|, and lead 52 to power line 43 causing the contact supporting element 5|] to operate so that the current-will be supplied' to pump motor I0, regardless of whether the water in thel carbonator is suiiiciently low to cause mercury sWitch62 to be closed. However, if the `water level in carbonator I1 is not at its upper limit, and

ii?, the thermostatically controlled switch 35 is position from .that just described as soon as the.

operator removes his hand therefrom and, thereby, `the circuits described will all open.

' .By the automatic and normally used circuit of Figure 2, which is set up when an operator moves movable contact 1I against xed contact 66, in

which position it will remain until manually returned to the open position shown, the circuit will.

to flow to pump motor I0 so that water will iiow through unit I5. y y

switch 35 will close when warm water enters the Thermostatically operated c oil I4 and current will then ow to valve opening coil 3| to openthe valve 29 so that a low pressure will be maintained in unit I5 and the water will be cooled to the desired low temperature. It will be observed that while valve opening coil 3| is directly responsive to thermostatically operated the motor lo but valve opening con 3| win remain eiective circuit through leads 65. 86. 58a and 55 until the temperature of the water in coil I 4 drops to too great an extent and thermostat 35 hereby opens. When this, occurs, coil 3| will be deener# gized and 'a higher pressure will be maintained in unit l5. When the switch 62 again closes, switchoperating coil 5| will again be energized to start motor I and if the water temperature is thigh enough, coil 3| will be energized. When motor l0 starts, Water entering'coil I4 will. of

course, cause switch 35 to close if it is open. .Y It will be clear that the pressure and temperature ranges used with the Figure 2 arrangement can be similar to those stated in connectiony with Figure 1. a

In some installations, the Figure Z-arrangement.

will not be as desirable as that of Figure 1 because, with the Figure 2 system, there may. be a lag in placing unit I under low pressure due`to the fact that energization of -coil 3| is, to a certain extent, responsive to the water temperature. However, the temperature of the water in coil I4 depends upon whether pump II is operating and if the pump stops, as occurs when the float rises to open switch62, the water temperature, will drop. Also, when the Dump starts, as when the float drops, the water temperature will immediately rise. Hence, even in the Figure 2 arrangement, the coil 3| is responsive to whether the pump and its motor Ill are actuated.

Figure 3 discloses another control circuit wherein the pressure in unit I5 is more directly andv immediately responsive to operation. of pump motor I 0 than the Figure 1 arrangement, By the Figure 3 system, the float controlledv mercury switch 62 is connected to the Contact 66 by al lead 'l5 andto switch holding coil 5| by a lead 16, Lead 16 is connected to contact 59 by a llead `'IL The movable contacts of switch 60 are' connected by a lead, I8 to common4 return line-80 of a three wire system also including lines 8| and 82. Coil 5I operates -to -close motor leads 83, 84,. andw and leads 86 and -8l connected to motor leads v83 and 85 place valve operating coil 3| lin parallel with the water pump motor I 0.' By this arrangement, when 'the float controlle'clvswitchy 6T causes motor I0 to be placed in operation,

valve opening coil 3| will immediately be energized to move valve 29 toits fully opened position so that maxlmumcooling can be exerted vupon the water moving through unit I5, When the water .level rises to open switch 62, the motor will stop and flow of waterwill be discontinued but temperature.

It will be observed that by the Figure- 3 arylo Figure 3 arrangement, the temperature o asoman energized through the parallel .and alternativelyy motor lll stops, valve- 29 may close sumciently to maintain a pressure of 36 lbs. in the unit with the result that they standing water will thereby likewise be maintained t 36".'V Hence, by the thewater canbe held constant regardless of whe er it' is owing or non-flowing. Therefore, if t is desired tondo so, the temperature o the water tact 'l0 is held vin engagement with contact 59, the water pump motor circuit will close and valve 2Q will be held open, all entirely independent of 'the position of float 62.

rangement, there is'no lag whatever in operation of valve opening coil 3| and the evaporatingpolnt di' the refrigerant is directly responsive to whether water is flowing. amount of heat must be removed from flowing water'than -from non-owing water to bring the two to the same temperature, it will be clear that even though a lower pressure is maintained in unit I5 while the water is flowing, the nonowing 'water can be maintai temperature by raising higher pressure. For eiample. a pressure of 32 lbs. can be maintained in unit I5 while the water is running to cool the water to 36. When Since `a greaterI d at the identicalV .B to asomewhat In the use of any of the automatic contact arrangements described above, if the pressure maintained in unit I5 when suction. valve .2B is wide open is such as to cool flowing water to 36, for example, the higher pressure maintained when valve 29 is more nearly closed will still be low enou h to cool the standing water to 36. It will be o vious that while water is iowing, the pressure of the refrigerant in unit I5 may be -so very low that a substantial volume of water can be cooled to a point close' tofreezing. but that when ow stops, a pressure sufiicient to provent freezing can be maintained. Thus, advanf Ii' .a thermostatically controlled switch such. as 35'in Figures l and 2 isA used, such switch can i be set to open when the temperature drops to about 33.

In the example disclosed. the invention is shown used with a heat exchange unit of the vwater cooling type. the unit. furthermore. being of the ooded type. As has been stated above, otherheat exchange elements can be controlled by the invention and, if cooling is to be per` formed. the.coo ling unit need not be of the flooded type. The terminology used -in the specication le for the purpose vof, description and not of limitation, the scope of the invention being defined in the claims. f

-This application' is a continuation-impart nl my application Serial No. 411,599, tiled September 19, 1941, I

I claim; 4 r

1. In a. heat exchange system .foruse with a heat exchange medium readily -vaporizable at ordinary temperatures, a heat exchange element to bring a. liquidto be treated and the medium into heat exchanging relation, means for delivering the liquid to be treated to said element, an actuating circuit for said liquid delivering means,

.and means in said actuating circuit to -maintain .the heat exchange medium within said heat ex- -cluange element at a plurality ofgdeflnite pressnres.

- 2.` In a heat exchange system for use with a heat exchange medium readily vaporizable at ordinary temperatures, a heat exchange elementl to bring a liquid to be treated and the medium into heat exchanging relation, means for delivering the liquid to betreated to vsaid element, an actuy 3. In a heat exchange system foruse with a heat exchange medium readily v aporizable at ordinary temperatures, a heat. exchange element to .bring a liquid to be treated and the medium into heat'exchanging relation, means for delivering 5 of liquid in said liquid receiving means, and l means controlled by said circuit to maintain the heat exchange medium at a plurality of deiinite pressures.

4. In a heat exchange system for use with a heat exchange medium readily vaporizable at orl dinary temperatures, a heat exchange element to bring a liquid to be treated and the medium'intoff heat exchanging relation, meansfor delivering the liquid to be treated to said element, means to receive the liquid from said heat exchange ele- .pressure o f the heat exchange medium.

ment, an actuating circuit forsaid liquid delivering means, means in said circuit responsive tothe quantity of liquid in said liquid receiving means andthe 'temperature of the liquid treated'by said heat exchange element, and .means controlled by said circuit to maintain the heat exchange rnedium at a plurality of denite pressures.

' 5. In a heat exchange system for use with a heat exchange medium readily vaporizable `atordinary temperatures, a -heat exchange element to bring a liquid to be treated and the medium into heat exchanging relation, means for delivering the liquid to be treated to said element, an actuating circuit i'or said liquid delivery means, and means solely responsive to flow of currentinsaid circuit to maintain themedium within said heat exchange element at a plurality of definite pressures.

6. In a heat exchange system for use with a heat exchange medium readily vaporizable at ordinary temperatures, a heat exchange element to i bring a liquid to be treated and the medium into heat exchanging relation, means-for delivering the liquid to be treated to said element, means to receive the treated liquid from said element, an

` actuating circuit for said liquid delivering means,

said circuit having means associated therewith responsive to the temperature of the treated liquid, means to maintain the heat exchange medium within said heat exchange element at a plurality of denite pressures, said last-named means being so connected in said circuit as to be I partially responsive to actuation of said liquid delivering means and partially responsive to said temperature controlled means'.

7. In a heat exchange system for use' with a heat exchange medium readily vaporizable at ordinary temperatures', a heat exchange element to bring a liquid to be treated and the medium into heat exchanging relation, means for delivering the liquid to be treated to said element, means/ff to maintain the heat exchanging characteristif of the heat exchange medium at definite factors, a pair of alternatively effective circuits for coricuits being responsive to operation of said liquid delivering means, and the other of said` circuits being responsive to the temperature of the treated liquid.-

8. In heat exchange medium readily vaporizableat ordinary temperatures, a heat exchange element to bring a liquid to be treated and the medium' into heat exchanging relation, means for delivering the liquid to be treated to said element, means to,v

receive the treated liquid from said element,

means to maintain the heat exchanging characteristics of the heat exchange medium at deilnite factors, a pair of alternatively effective circuits for controlling said last-named means, one of said circuits being responsive to thev level 'of liquid in said liquid receiving means, and the other of said circuits being responsive vto the temperature of the treated liquid.u

9. In a heat exchange system for use with a heat exchange medium, a heat exchange element to bring .the medium and a liquid to be treated in heat exchanging relation, means to deliver a liquid to be treated to said element, means to receive treated liquid from the element, means responsive to the level of liquid in said treated liquid receiving means to control operation of said liquid ldelivery means, and means including thermostatic means directly responsive to the temperature ofthe treated liquid to control the 1Q. In a heat exchange system for use with a heat exchange medium readily vaporizable at ordinary temperatures, a-heat exchange element to bring a liquid to be treated and the medium into'heat exchanging relation, means for delivering the liquid to be treated to said element, means to receive theY treated liquid from said element, an Aactuating circuit for saidA liquid delivering means, means controlled by said circuit to maintain the heat exchange medium within said heat exchange element at a plurality vof denite pressures, said circuit having means associated therel with responsive to thev quantity of liquid in said liquid receiving means, additional means assocircuit responsive to the temperciated with said ature of the treated liquid, said two last-named means being so connected that the actuating circuit will be closed when the liquid in said liquid receiving means reaches a predetermined level and will open when the temperature of the treated close when the liquid in said receiving means drops to a predetermined level, means in parallel with said circuit including a second float operated switch in said receiving means to maintain the heat exchange medium Within said heat exchange element ata predetermined pressure, and

a second circuit to maintain the exchange medium at said predetermined pressure comprising Q9 a therfmostatic switch responsive tothe temperatrolling said last-named means, one of vsaid cir- 75 ordinary temperatures, a heat nre/.df the liquid.

JVAl2. In. a heat exchange system for use with a heat exchange medium readily vaporizable at ordinary temperatures, a heat exchange element to bring a liquid to be treated and the 'medium into heat exchanging relation, means for delivering the liquid to'be treated to said element, an

actuating circuit for said liquid delivering means, a valve to control iiow of operation of said valve.

13.v In a heat exchange system for use with a heat exchange medium readily vaporizable at exchange element for delivering the medium with respecta heat exchange system for use with a to said heat exchange element, and means in said actuating circuit in parallel with said liquid de` l livering means to control in bring a liquid to be treated landthe medium into -heat exchanging relation, means for deliver- Y ing the liquid lto be treated to said element, an 'actuating circuit for said liquid delivering means,

a valve to control ow of the medium with re-A spect to said heat exchange element and adapted to lower the pressure of the medium in said element when in opened position, and means controlled by said actuating circuit to open said valve F whensaid liquid delivering means is operating.

14. In a heat exchange system for use with a ordinary temperatures', a heat exchange element to bring a liquid vto be treated and the medium into heat exchanging relation, means for deliver ing the liquid tolbe'treated to said element. means y to maintain the pressure of said medium in said elementa't predetermined points, and means to operate said last-named means to maintain the pressure ofthe medium ata low `pressure when said means -for delivering the liquid 'to-said e1e' ment is operating.

. 15.` In a heat exchange system for use with a heat exchange mediumreadily vaporizable at ordinary temperatures, a heat 'exchange element to bring aiiquid to be treated and themedium into heat exchange m'edium readily vaporizable at v the liquid to be treated to said element, an actu- 16. In a heat exchange system for use with a heat exchange medium vreadily vaporizable at ordinary temperatures, a heat exchange element to bring a. liquid to be treated and the medium intovheat exchanging relation, means for deliver-` ing the liquid to be treated to said element, means to receive the treated liquid -from said element.

A an actuating circuit for said liquid delivering heat exchanging relation',- meansior delivering means comprising a float operated switch adapted to close when the liquid in said receiving means drops to a predetermined level, a thermostatic switch responsive to the temperature 'of the liquid in said element, and means directly responsive to said thermostatic switchto maintain the heat exchange medium within said heat exchangeelen ment at a predetermined pressure.

ROBERT J. STEWART. l 

